ABSTRACT The NIH is funding the largest genotype-based randomized clinical trial (RCT) in cardiovascular (CV) diseases (ClinicalTrials.gov Identifier: NCT01742117) involving 5,270 subjects undergoing percutaneous coronary intervention (PCI). TAILOR PCI (5U01HL128606-02) is a RCT of a CYP2C19 genotype-directed dual antiplatelet therapy (DAPT) strategy with either clopidogrel or ticagrelor versus a guideline-directed usual care strategy with clopidogrel based DAPT after PCI. The trial is currently enrolling patients (n=4071 as of May 12th, 2017) who are followed for 1 year after randomization by study coordinator (SC) calls at 1, 6 and 12 months to capture major adverse CV events (MACE) and bleeding events. The proposed study intends to seamlessly transition TAILOR PCI subjects to a registry in order to follow them beyond one-year post PCI by using validated, state of the art digital solutions. The aims of such a registry would be to assess the prescription patterns of DAPT beyond one year after PCI and to determine whether CYP2C19 genotype identifies a group of patients that will most benefit from DAPT extended beyond one year after PCI. Extended DAPT requires an individualized approach to balance the benefits of reducing ischemic events with the risks of bleeding and to date such individualization has not incorporated CYP2C19 genotype status. The registry will also attempt to discover whether digital technology tracking heart rate, activity, and 6 minute walk test distance can be used to predict MACE or bleeding events. A novel validated digital platform for consenting, follow-up and outcomes ascertainment?the Eureka Mobile Research platform (www.info.eurekaplatform.org), which is funded by the NIH (5U2CEB021881), will be used for creating the registry. To accomplish this goal since the TAILOR PCI trial is currently recruiting subjects, we will divide the proposed study into 3 components: 1) Digitally consent a retrospective cohort (n=2097) who have completed 1 year follow up in TAILOR PCI and assess for beyond 1 year post PCI outcomes by SC calls and medical record review. 2) Digitally consent a prospective cohort (projected n=1334) who are yet to complete 1 year follow up and assess outcomes by a smartphone-based geo-fenced tracking application that will be compared to hospitalizations detected by SC calls. 3) Consent TAILOR PCI subjects enrolled in Korea and Mexico (projected n=1839) by mail and assess outcomes by SC calls and medical record review. In summary, a registry based on an existing large, pragmatic, RCT using validated digital technology for enrollment and consent will be established within which a validated, smartphone tracking application will be utilized to capture MACE and bleeding events.